The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Al—Si based cast aluminum alloys have widespread applications for structural components in the automotive, aerospace, and general engineering industries because of good castability, corrosion resistance, machinability, and high strength-to-weight ratio. Regarding castability, alloy compositions having lower silicon content have been thought to inherently produce poor castings due to a wider freezing range and the reduced latent heat. Alternatively, alloy compositions having higher Silicon content are increasingly difficult to machine and have lower ductility and fracture toughness due to coarser primary silicon particles. In general, aluminum alloy casting performance is based on several factors including alloy composition, casting and solidification conditions, and post-casting process or heat treating.
In attempting to expand or improve the use of aluminum alloys in additional applications that can reap the benefits that aluminum alloys offer, existing aluminum alloy casting composition and processes have fallen short of success in high temperature applications. The overwhelming problem with using aluminum alloy castings in high temperature applications is the tendency for the material to change properties in service. In designing cast parts for such applications, one of the most important aspects of material properties is exactly that the material properties stay unchanged in service. However, to this end currently available commercial aluminum alloys fail to provide such material property stability.
Accordingly, there is a need in the art for an aluminum alloy composition and manufacturing method that has improved initial material properties while maintaining or stabilizing the material properties throughout the service life of the casting in a high temperature application.